Camptothecin and derivatives thereof are cytotoxic agents, which exhibit antitumor activity primarily by inhibiting topoisomerase I, a clinically validated drug target which is usually overexpressed in malignant cells. Camptothecin and its derivatives act by interfering with the unwinding of supercoiled DNA by the cellular enzyme topoisomerase I which triggers events leading to apoptosis and programmed death in malignant cells.